5Tochigi Prefectural Minaminasu Agriculture Promotion Office, Karasuyama, Tochigi, 321-0621, Japan We constructed a genetic linkage map for the carnation (Dianthus caryophyllus L.) on the basis of random amplified polymorphic DNA (RAPD) and simple sequence repeat (SSR) by using a resistance-segregating population of 134 progeny lines that were derived from a cross between 'Carnation Nou No. 1' (a carnation breeding line resistant to bacterial wilt) and 'Pretty Favvare' (a susceptible cultivar). The linkage map consisted of 137 RAPD and 9 SSR markers. Linkage analysis revealed that 124 loci could be mapped to 16 linkage groups that extended for 605.0 centiMorgans (cM). The average interval between two loci was 4.9 cM. Quantitative trait loci (QTL) analysis was applied to evaluations of resistance to bacterial wilt that were replicated 8 times. The QTL that we reported previously with a large effect on resistance was detected on group 6 which accounted for 60.5% of the total phenotypic variance with a LOD score 23.46. Two other QTLs with small effects were detected on groups 2 and 5 with LOD scores of 2.32 and 2.87, respectively. These results suggest that resistance to bacterial wilt in carnation is related to one major and at least two minor genes. This study is the first report on the construction of a linkage map of the carnation.

We investigated longevity, ethylene production and ethylene sensitivity of flowers among 42 pot carnation cultivars. Our results indicate that there was a large genetic variability in flower longevity and ethylene synthesis in pot carnation cultivars. Five cultivars ('Polaris', 'Camille Pink', 'Chiffon', 'Bambino' and 'Nina') had a mean flower longevity of more than 9.7 days. These cultivars with long flower longevity showed low ethylene production at senescence and showed neither petal in-rolling nor rapid wilting, which are typical symptoms of ethylene-dependent senescence. Instead, these flowers faded and turned brown along their petal edges. Significant negative correlations were observed between flower longevity and ethylene production at senescence, and between flower longevity and autocatalytic ethylene production. Although large genetic variability in ethylene sensitivity was observed in diploid cultivars, there was no correlation between flower longevity and ethylene sensitivity. Our data showed that polyploidy level in pot carnation cultivars does not have a profound influence on flower longevity or ethylene sensitivity. This study suggests that improvement of flower longevity of pot carnation using cross breeding techniques would be feasible.

Flower type of single or double is one of the important characters in carnation (Dianthus caryophyllus L.). Therefore, we selected random amplified polymorphic DNA (RAPD) markers associated with the genes controlling flower type in a segregated population of 127 progeny plants derived from a cross between 'Carnation Nou No. 1' (double) and 'Pretty Favvare' (single), which were used for construction of our genetic linkage map in carnations. Four RAPD markers identified by bulked segregant analysis of 696 primers were linked to a recessive gene controlling a single flower type derived from a wild species, D. capitatus ssp. andrzejowskianus. In particular, three RAPD markers, OM19-800, AT90-1000, DT52-700 appeared in all 45 single plants individually, but not in any of the double plants, indicating these three markers were tightly linked to the gene controlling the single flower type. The RAPD marker AT90-1000 was successfully converted to a sequence-tagged site (STS) marker. Linkage analysis revealed that this single gene was located on group 16 in our genetic linkage map. However, the STS marker was not detected in the four single flowered carnation cultivars. This result indicates that this STS marker is highly specific for the single gene derived from D. capitatus ssp. andrzejowskianus.